I only keep the pre-1950 dated coins unless they are 50-D and 51-D, all the S mints and the '55 philly. Others all go right back into the coin machine. Just today I got a '54-D in change and turned around and spent it later.
I keep the pre-60's to the point that I have a tube of each date/mm. If I find a nice one in a roll I replace a lesser grade one with the new one.
Been sorting nickels for years. Believe that I've been saving the pre-'59 for over 30 years. Have a group of them. Been told many years ago that they were getting scarce and lately I've found that I don't see to many of them any more.
I save anything from 1960 back including 1960s. I hoard these nickels, no matter what condition they are in. Some of the loveliest coins are the most circulated. Don't know why I save the '60s but I also save '60 pennies (when I found out about the small date variety I looked through my bottle of '60s and found 5 or 6 small date '60s.)
Doug Rogers: I have noticed the abundance of 1964 nickels that they have become the bane of my existence. Also, when you mention collecting for fun, is there really another good reason? There are better ways to make money than to hoarde coins. If you're not having fun there is no reason to be in the hobby.
1965 quarters (and for a few years after '65) do indeed have a different look to them. When they are in a pile of shiny clad quarters, they can deceive you into thinking they are silver quarters until you take a better look at them. And yes, it appears that the mint used a different metal alloy for nickels in the '40s than they did in the '70s. Not sure when the changeover took place. I can tell a well circulated '40s nickel from a mile away. They seem to take on a yellowish tinge to them. Every now or then the '64 nickel will trick me into thinking it's older. So perhaps 64/65 was the year the content changed.